In segmented DACs, the gain (amplitude) mismatch between different segments causes nonlinear distortion, which may be perceived as an increase in noise floor for large narrowband signals, or manifest itself as nonlinear distortion for broadband signals or digitally backed-off signals, which may also be narrowband.
Even with element-wise calibration (i.e. calibration of all DAC cells), a sufficient accuracy at the segment boundaries cannot be achieved easily in practical implementations. Gain mismatch between different DAC segments may, hence, be the dominant source of nonlinearity and/or noise floor, especially for wideband signal synthesis applications.
Hence, there may be a desire for improved gain mismatch correction.